Melbourne17.12 Surface water allocation diversion - urban water system

Supporting Information

The volume presented (353,431 ML) represents the volume of water diverted from surface water storages for distribution via the urban water supply system under bulk entitlements held by Melbourne's retail water authorities.

The volume includes:

water delivered to retail authorities City West Water, South East Water, Yarra Valley Water and Western Water from water storages operated by Melbourne Water

water delivered to Western Water from water storages operated by Southern Rural Water.

water diverted by Western Water for Marriages, Romsey and Lancefield water treatment plants, and from Macedon storage for Woodend.

The breakdown of allocated diversions to the urban water system in the Melbourne region during the 2010–11 year are presented in the following table.

Surface water diversions during the 2010–11 year

Authority

Provided to

Quality

Volume (ML)

Melbourne Water

City West Water

Potable

92,562

South East Water

Potable

123,390

Non-potable

72

Yarra Valley Water

Potable

127,314

Non-potable

307

Western Water

Potable

7,881

Southern Rural Water

Western Water

Potable

1,905

Total

353,431

Quantification Approach

Melbourne Water

Data Source

Melbourne Water waterworks database.

Provided by

Melbourne Water.

Method

Volumes were calculated using the weekly metered volume of bulk water supplied by Melbourne Water to retail water authorities City West Water, South East Water, Yarra Valley Water and Western Water.

Metered volumes are based on Melbourne Water bulk meters.

Assumptions, Limitations, Caveats and Approximations

The third-party pipe transfer of 45 ML from Melbourne Water to supply Southern Rural Water for the Bacchus Marsh Irrigation District via Western Water infrastructure during the 2010–11 year is not included in this volume, as it does not represent water imported/received by Western Water.

Uncertainty Information

Reliability and accuracy for metered volume of potable water delivered is +/– 5% i.e. Grade 2 (according to Water Industry Regulatory Audits, October 2011).

Southern Rural Water

Data Source

Western Water information technology database. Southern Rural Water database.

Provided by

Western Water.

Method

Volumes were calculated using the weekly metered volume of surface water delivered from Merrimu, Rosslynne and Pykes Creek, and treated at the Myrniong (Pykes Creek Reservoir), Merrimu and Rosslynne water treatment plants.

Assumptions, Limitations, Caveats and Approximations

The third-party pipe transfer of 45 ML from Melbourne Water to supply Southern Rural Water for the Bacchus Marsh Irrigation District via Western Water infrastructure during the 2010–11 year is not included in this volume, as it does not represent water imported/received by Western Water.

Western Water also diverted an additional 830 ML from Romsey, Marriages, Lancefield and Macedon storages that they operate.

Uncertainty Information

Uncertainty is +/– 5% in accordance with the manufacturer's annual bulk meter test.

Comparative year

This item corresponds to line item 14.7.4 Allocation/claim diversion of regulated flows – urban water access entitlement/arrangement reported in the 2010 Account. There was no change to the volume reported in the 2010 Account. The restated comparative year volume is 360,816 ML.